Oil-in-Oil emulsified polymeric implants containing a hypotensive lipid and related methods

ABSTRACT

Biocompatible intraocular implants, such as microparticles, include a prostamide component and a biodegradable polymer that is effective in facilitating release of the prostamide component into an eye for an extended period of time. The prostamide component may be associated with a biodegradable polymer matrix, such as a matrix of a two biodegradable polymers. Or, the prostamide component may be encapsulated by the polymeric component. The present implants include oil-in-oil emulsified implants or microparticles. Methods of producing the present implants are also described. The implants may be placed in an eye to treat or reduce a at one symptom of an ocular condition, such as glaucoma.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.10/837,260, filed Apr. 30, 2004, the entire contents of which are herebyincorporated by reference.

BACKGROUND

The present invention generally relates to devices and methods is treatan eye of a patient, and more specifically to intraocular implants ormicoroparticles that provide extended release of a therapeutic agent toan eye in which the implant is placed to treat ocular hypertension, suchas by reducing or at least maintaining intraocular pressure, and tomethods of making and using such implants.

Ocular hypotensive agents are useful in the treatment of a number ofvarious ocular hypertensive conditions, such as post-surgical andpost-laser trabeculectomy ocular hypertensive episodes, glaucoma, and aspresurgical adjuncts.

Glaucoma is a disease of the eye characterized by increased intraocularpressure. On the basis of its etiology, glaucoma has been classified asprimary or secondary. For example, primary glaucoma in adults(congenital glaucoma) may be either open-angle or acute or chronicangle-closure. Secondary glaucoma results from pre-existing oculardiseases such as uveitis, intraocular tumor or an enlarged cataract.

The underlying causes of primary glaucoma are not yet known. Theincreased intraocular tension is due to the obstruction of aqueous humoroutflow. In chronic open-angle glaucoma, the anterior chamber and itsanatomic structures appear normal, but drainage of the aqueous humor isimpeded. In acute or chronic angle-closure glaucoma, the anteriorchamber is shallow, the filtration angle is narrowed, and the iris mayobstruct the trabecular mesh work at the enhance of the canal ofSchlemm. Dilation of the pupil may push the root of the iris forwardagainst the angle, and may produce pupillary block and thus precipitatean acute attack. Eyes with narrow anterior chamber angles arepredisposed to acute angle-closure glaucoma attacks of various degreesof severity.

Secondary glaucoma is caused by any interference with the flow ofaqueous humor from the posterior chamber into the anterior chamber andsubsequently, into the canal of Schlemm. Inflammatory disease of theanterior segment may prevent aqueous escape by causing completeposterior synechia in iris bombs and may plug the drainage channel withexudates. Other common causes are intraocular tumors, enlargedcataracts, central retinal vein occlusion, trauma to the eye, operateprocedures and intraocular hemorrhage.

Considering all types together, glaucoma occurs in about 2% of allpersons over the age of 40 and may be asymplotic for years beforeprogressing to rapid loss of vision. In cases where surgery is notindicated, topical beta-adrenoreceptor antagonists have traditionallybeen the drugs of choice for treating glaucoma.

Prostaglandins were earlier regarded as potent ocular hypertensives;however, evidence accumulates in the last two decades shows that someprostaglandins are highly effective ocular hypotensive agents and areideally suited for the long-term medical management of glaucoma. (See,for example, Starr, M. S. Exp. Eye Res. 1971, 11, pp. 170-177; Bito, L.Z. Biological Protection with Prostaglandins Cohen, M. M., ed., BocaRaton, Fla., CRC Press Inc., 1985, pp. 231-252; and Bito, L. Z., AppliedPharmacology in the Medical Treatment of Glaucomas Drance, S. M. andNeufeld, A. H. eds., New York, Grune & Stration, 1984, pp. 477-505).Such prostaglandins include PGF_(2α), PGF_(1α), PGE₂, and certainlipid-soluble esters, such as C₁ to C₅ alkyl esters, e.g. 1-isopropylester, of such compounds.

In U.S. Pat. No. 4,599,353 certain prostaglandins, in particular PGE₂and PGF_(2α) and the C₁ to C₅ alkyl esters of the latter compound, werereported to possess ocular hypotensive activity and were recommended foruse in glaucoma management.

Although the precise mechanism is not yet known, recent experimentalresults indicate that the prostaglandin-induced reduction in intraocularpressure results from increased uveoscleral outflow [Nilsson et al.,Invest. Ophthalmol. Vis. Sci. 28 (suppl), 284 (1987)].

The isopropyl ester of PGF_(2α) has been shown to have significantlygreater hypotensive potency than the parent compound, which wasattributed to its more effective penetration through the cornea. In1987, this compound was described as “the most potent ocular hypotensiveagent ever reported.” [See, for example, Bito, L. Z., Arch. Ophthalmol.105, 1036 (1987), and Siebold et al., Prodrug 5, 3 (1989)].

Whereas prostaglandins appear to be devoid of significant intraocularside effects, ocular surface (conjunctival) hyperemia and foreign-bodysensation have been consistency associated with the topical ocular useof such compounds, in particular PGF_(2α) and its prodrugs, e.g. its1-isopropyl ester, in humans. The clinical potential of prostaglandinsin the management of conditions associated with increased ocularpressure, e.g. glaucoma, greatly limited by these side effects.

Certain prostaglandins and their analogs and derivatives, such as thePGF_(2α) derivative latanoprost, sold under the trademark Xalatan®, havebeen established as compounds useful in treating ocular hypertension andglaucoma. However, latanoprost, the first prostaglandin approved by theUnited States Food And Drug Administration for this indication, is aprostaglandin derivative possessing the undesirable side effect ofproducing an increase in brown pigment in the iris of 5-15% of humaneyes. The change in color results from an increased number ofmelanosomes (pigment granules) within iridial melanocytes. See e.g.,Watson et al, Ophthalmology 103:126 (1996). While it is still unclearwhether this effect has additional and deleterious clinicalramifications, from a cosmetic standpoint alone such side effects areundesirable.

Certain phenyl and phenoxy mono, tri and tetra nor prostaglandins andtheir 1-esters are disclosed in European Patent Application 0,364,417 asuseful in the treatment of glaucoma or ocular hypertension.

In a series of United States patent applications assigned to Allergen,Inc. prostaglandin esters with increased ocular hypotensive activityaccompanied with no or substantially reduced side-effects are disclosed.U.S. patent application Ser. No. (U.S. Ser. No. ) 386,835 (filed Jul.27, 1989), relates to certain 11-acyl-prostaglandins, such as11-pivaloyl, 11-acetyl, 11-isobutyryl, 11-valeryl, and 11-isovalerylPGF_(2α). Intraocular pressure reducing 15-acyl prostaglandins aredisclosed in U.S. Pat. No. 357,394 (filed May 25, 1989). Similarly,11,15-9,15- and 9,11-diesters of prostaglandins, for example11,15-dipivaloyl PGF_(2α) are known to have ocular hypotensive acuity.See U.S. Ser. No. 385,845 fifed Jul. 27, 1990, now U.S. Pat. Nos.4,434,274; 584,370 which is a continuation of U.S. Ser. No. 386,312, andU.S. Ser. No. 585,284, now U.S. Pat. No. 5,034,413 which is acontinuation of U.S. Ser. No. 386,834, where the parent applicationswere filed on Jul. 27, 1989.

Woodward et al U.S. Pat. Nos. 5,688,819 and 6,403,649 disclose certaincyclopentane heptanoic acid, 2-cycloalkyl or arylalkyl compounds asocular hypotensives. These compounds, which can properly becharacterized as hypotensive lipids, are effective in treating ocularhypertension.

As one example, the prostamide analog, bimatoprost, has been discoveredto be effective in reducing intraocular pressure possibly by increasingthe aqueous humour outflow of an eye (Woodward el al., AGN 192024(Lumigan®): A Synthetic Prostamide Analog that Lowers PrimateIntraocular Pressure by Virtue of Its Inherent Pharmacological Activity,ARVO 2002; (CD-ROM): PROS; Chen et al., Lumigan®: A Novel Drug forGlaucoma Therapy, Optom In Pract, 3:95-102 (2002); Coleman et al., A3-Month Randomized Controlled Trial of Bimatoprost (LUMIGAN) versusCombined Timolol and Dorzolarmide (Cosopt) in Patients with Glaucoma orOcular Hypertension, Ophthalmology 110(12): 2362-8 (2003); Brubaker,Mechanism of Action of Bimatoprost (Lumigan®), Surv Ophthalmol 45 (Suppl4):S347-S351 (2001); and Woodward et al., The Pharmacology ofBimatoprost (Lumigan®), Surv Ophthalmol 45 (Suppl 4) S337-S345 (2001).

Bimatoprost is an analog (e.g., a structural derivative) of a naturallyoccurring prostamide. Bimatoprost's chemical name is (Z)-7-[(1R, 2R, 3R,5S-3,5-Dihydroxy-2-[1E, 3S)-3-hydroxy-5-phenyl-1-pentenyl]cyclopentyl]-5-N-ethylheptenamide, and it has a molecularweight of 415.58. Its molecular formula is C₂₅H₃₇NO₄. Bimatoprost isavailable in a topical ophthalmic solution under the tradename Lumigan®(Allergan, Inc.). Each mL of the solution contains 0.3 mg of bimatoprostas the active agent, 0.05 mg of benzalkonium chloride (BAK) as apreservative, and sodium chloride, sodium phosphate, dibasic; citricacid; and purified water as inactive agents.

Biocompatible implants for placement in the eye have been disclosed in anumber of patents, such as U.S. Pat. Nos. 4,521,210; 4,853,224;4,997,652; 5,164,188; 5,443,505; 5,501,856; 5,766,242; 5,824,072;5,869,079; 6,074,661; 6,331,313; 6,369,116; and 6,699,493.

It would be advantageous to provide eye implantable drug deliverysystems, such as intraocular implants, and methods of using suchsystems, that are capable of releasing a therapeutic agent, such as ahypotensive agent, at a sustained or controlled rate for extendedperiods of time and in amounts with few or no negative side effects.

SUMMARY

The present invention provides new drug delivery systems, and methods ofmaking and using such systems, for extended or sustained drug releaseinto an eye, for example, to achieve one or more desired therapeuticeffects. The drug delivery systems are in the form of implants orimplant elements that may be placed in an eye. The present systems andmethods advantageously provide for extended release times of one or moretherapeutic agents. Thus, the parent in whose eye the implant orpopulation of implants has been placed receives a therapeutic amount ofan agent for a long or extended time period without requiring additionaladministrations of the agent. For example, the patient has asubstantially consistent level of therapeutically active agent availablefor consistent treatment of the eye over a relatively long period oftime, for example, on the order of at least about one week, such asbetween about two and about six months after receiving an implant. Suchextended release times facilitate obtaining successful treatmentresults.

Intraocular implants in accordance with the disclosure herein comprise atherapeutic component and a drug release sustaining component associatedwith the therapeutic component. In accordance with the presentinvention, the therapeutic component comprises, consists essentially of,or consists of, a prostamide component, such as a prostamide derivativethat is effective in reducing or maintaining a reduced intraocularpressure in a hypertensive eye. The drug release sustaining component isassociated with the therapeutic component to sustain release of anamount of the prostamide component into an eye in which the implant isplaced. The amount of the prostamide component is released into the eyefor a period of time greater than about one week after the implant isplaced in the eye and is effective in treating or reducing at least onesymptom of an ocular condition of an eye. Advantageously, the presentintraocular implants may be effective in relieving a hypertensive eye byreducing the intraocular pressure of the eye or maintaining theintraocular pressure at a reduced level.

Embodiments of the present implants can be understood from the followingdescription and claims.

In one embodiment, the intraocular implants comprise prostamidecomponent and a biodegradable polymer matrix. The prostamide componentis associated with a biodegradable polymer matrix that releases drug ata rate effective to sustain release of an amount of the prostamidecomponent from the implant effective to treat an ocular condition. Theintraocular implant is biodegradable or bioerodible and provides asustained release of the prostamide component in an eye for extendedperiods of time, such as for more than one week, for example for aboutthree months or mom and up to about six months or more.

The biodegradable polymer component of the foregoing implants may be amixture of biodegradable polymers, wherein at least one of thebiodegradable polymers is a polylactic acid polymer having a molecularweight less than 64 kiloDaltons (kD). Additionally or alternatively, theforegoing implants may comprise a first biodegradable polymer of apolylactic acid, and a different second biodegradable polymer of apolylactic acid. Furthermore, the foregoing implants may comprise amixture of different biodegradable polymers, each biodegradable polymerhaving an inherent viscosity in a range of about 0.2 deciliters/gram(dl/g) to about 1.0 dl/g.

The prostamide component of the implants disclosed herein may includeprostamide derivatives, such as a prostamide analog, that are effectivein treating ocular conditions. One example of a suitable prostamidederivative is bimatoprost or a salt thereof. In addition, thetherapeutic component of the present implants may include one or moreadditional and different therapeutic agents that may be effective intreating an ocular condition.

A method of making the present implants involves combining or mixing theprostamide component with a biodegradable polymer or polymer. Themixture may then be extruded or compressed to form a single composition.The single composition may than be processed to form individual implantssuitable for placement in an eye of a patient.

A method of making the present implants may also include using anoil-in-oil emulsion process to form the implants. Such methods may beparticularly useful in forming microparticles and the like. Thus, anembodiment of the present invention relates to methods of makingmicroparticles using an oil-in-oil emulsion process and microparticlesso produced, as described herein.

The implants, including a population of microparticles, may be placed inan ocular region to treat a variety of ocular conditions. For example,the implants may be effective in reducing ocular hypertension, andthereby may be effective in reducing at least one symptom of an ocularcondition associated with an increased intraocular pressure.

Kits in accordance with the present invention may comprise one or moreof the present implants, and instructions for using the implants. Forexample, the instructions may explain how to administer the implants toa patient, and types of conditions that may be treated with theimplants.

The present invention also encompasses the use of the present implantsin treating a patient, such as in treating one or more of the conditionsor diseases set forth herein, as well as medicaments, which areoil-in-oil emulated implants or microparticles, for treating an ocularcondition of a patient. The invention also encompasses the use of aprostamide component and a polymeric component, as described herein, inthe manufacture of a medicament for treating a patient.

Each and every feature described herein, and each and every combinationof two or more of such features, is included within the scope of thepresent invention provided that the features included in such acombination are not mutually inconsistent. In addition, any feature orcombination of features may be specifically excluded from any embodimentof the present invention.

Additional aspects and advantages of the present invention are set forthin the following description and claims, particularly when considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is flow chart of a method of making microspheres.

FIG. 2A is the chemical structure of bimatoprost.

FIG. 2B is the chemical structure of 15β bimatoprost.

FIG. 2C is the chemical structure of 5,6-trans bimatoprost isomer.

FIG. 2D is the chemical structure of the C1 acid of bimatoprost.

FIG. 2E is the chemical structure of triphenyphosphine oxide.

FIG. 2F is the chemical structure of 15-Keto bimatoprost.

FIG. 3A is a chromatogram of a bimatoprost standard.

FIG. 3B is a chromatogram of nom-sterilized bimatoprost microparticles.

FIG. 3C is a chromatogram of sterilized bimatoprost microparticles.

FIG. 3D is a chromatogram of non-sterilized placebo compositions.

FIG. 3E is a chromatogram of sterilized placebo compositions.

FIG. 4A is a graph of volume % as a function of particle diameter.

FIG. 4B is a graph of number % as a function of particle diameter.

FIG. 4C is a graph of volume % as a function of particle diameter for adifferent batch of microparticles than shown in FIG. 4A.

FIG. 4D is a graph of number % as a function of particle diameter forthe batch of FIG. 4C.

FIG. 5A is a photograph of one batch of sterile microspheres.

FIG. 5B is a photograph of a different batch of sterile microspheresother than the batch of FIG. 5A.

FIG. 5C is a photograph of of non-sterile microspheres.

FIG. 5D is a photograph of sterile microspheres.

FIG. 5E is a photograph of a non-sterile batch of microspheres.

FIG. 5F is a photograph of sterile microspheres.

FIG. 6 is a graph percent bimatoprost released as a function of time.

DESCRIPTION

As described herein, controlled and sustained administration of atherapeutic agent through the use of one or more intraocular implants,including microparticles or microparticle implants, may improvetreatment of undesirable ocular conditions. The implants andmicroparticles comprise a pharmaceutically acceptable polymericcomposition and are formulated to release one or more pharmaceuticallyactive agents, such as a prostamide, a prostamide derivative, such as aprostamide analog, or other intraocular pressure lowering agent, over anextended period of time. The implants are effective to provide atherapeutically elective dosage of the agent or agents directly to aregion of the eye to treat or prevent one or more undesirable ocularconditions. Thus, with a single administration, therapeutic agents willbe made available at the site whom they are needed and will bemaintained for an extended period of time, rather than subjecting thepatent to repeated injections or repeated administration of topicaldrops.

An intraocular implant or microparticle in accordance with thedisclosure herein comprises a therapeutic component and a drug releasesustaining component associated with the therapeutic component. Inaccordance with the present invention, the therapeutic componentcomprises, consists essentially of, or consists of, a prostamidecomponent. The drug release sustaining component is associated with thetherapeutic component to sustain release of an effective amount of theprostamide component into an eye in which the implant or microparticleis placed. The amount of the prostamide component is released into theeye for a period of time greater than about one week after the implantor microparticle is placed in the eye, and is effective in treating orreducing a symptom of an ocular condition.

Definitions

For the purposes of this description, we use the following terms asdefined in this section, unless the context of the word indicates adifferent meaning.

As used herein, an “intraocular implant” refers to a device or elementthat is structured, sized, or otherwise configured to be placed in aneye. Intraocular implants are generally biocompatible with physiologicalconditions of an eye and do not cause adverse Side effects. Intraocularimplants may be placed in an eye without disrupting vision of the eye.Implants refer to elements that have maximum dimensions that are on theorder of millimeters as well as elements that have maximum dimensions onthe order of micrometers. Micrometer sized elements may be understood tobe microparticles. Microparticles have a maximum dimension, such asdiameter or length, less than 1 mm. For example, microparticles can havea maximum dimension less than about 500 μm. Microparticles may also havea maximum dimension no greater than about 200 μm, or may have a maximumdimension from about 30 μm to about 50 μm, among other sizes.

As used herein, a “therapeutic component” refers to a portion of anintraocular implant comprising one or more therapeutic agents orsubstances used to treat a medical condition of the eye. The therapeuticcomponent may be a discrete region of an intraocular implant, or it maybe homogenously distributed throughout the implant. The therapeuticagents of the therapeutic component are typically ophthalmicallyacceptable, and are provided in a form that does not cause adversereactions when the implant is placed in an eye.

As used herein, a “prostamide component” refers to a portion of anintraocular implant that comprises one or more prostamides, one or moreprostamide derivatives, such as a prostamide analog, salts thereof, andmixtures thereof. A prostamide derivative is a compound that containsthe essential elements of the prostamide from which it is derived inorder to provide a therapeutic effect. A prostamide derivative includesprostamide analogs, and can be identified using any conventional methodsknown by persons of ordinary skill so the art used to evaluate theefficacy of a prostamide. For example, therapeutically effectiveprostamide derivatives can be identified by applying the prostamidederivative to an eye with increased intraocular pressure, and evaluatingwhether the intraocular pressure decreases after the application. Aprostamide component may also include one or more prostaglandin analogs.

As used herein, a “drug release sustaining component” refers to aportion of the intraocular implant that is effective to provide asustained release of the therapeutic agents of the implant. A drugrelease sustaining component may be a biodegradable polymer matrix, orit may be a coating covering a core region of the implant that comprisesa therapeutic component.

As used herein, “associated with” means mixed with, dispersed within,coupled to, covering, or surrounding.

As used herein, an “ocular region” or “ocular site” refers generally toany area of the eyeball, including the anterior and posterior segment ofthe eye, and which generally includes, but is not limited to, anyfunctional (e.g., for vision) or structural tissues found in theeyeball, or tissues or cellular layers that partly or completely linethe interior or exterior of the eyeball. Specific examples of areas ofthe eyeball in an ocular region include the anterior chamber, theposterior chamber, the vitreous cavity, the choroid, the suprachoroialspace, the conjunctiva, the subconjunctival space, the episcleral space,the intracorneal space, the epicorneal space, the sclera, the parsplana, surgically-induced avascular regions, the macula, and the retina.

As used herein, an “ocular condition” is a disease, ailment or conditionwhich affects or involves the eye or one of the parts or regions of theeye. Broadly speaking the eye includes the eyeball and the tissues andfluids which constitute the eyeball, the periocular muscles (such as theoblique and rectus muscles) and the portion of the optic nerve which iswithin or adjacent to the eyeball.

An anterior ocular condition is a disease, ailment or condition whichaffects or which involves an anterior (i.e. front of the eye) ocularregion or site, such as a periocular muscle, an eye lid or an eye balltissue or fluid which is located anterior to the posterior wall of thelens capsule or ciliary muscles. Thus, an anterior ocular conditionprimarily affects or involves the conjunctiva, the cornea, the anteriorchamber, the iris, the posterior chamber (behind the retina but in frontof the posterior wall of the lens capsule), the lens or the lens capsuleand blood vessels and nerve which vascularize or innervate an anteriorocular region or site.

Thus, an anterior ocular condition can include a disease, ailment orcondition, such as for example, aphakia; pseudophakia; astigmatism;blepharospasm; cataract; conjunctival diseases; conjunctivitis; cornealdiseases; corneal ulcer; dry eye syndromes; eyelid diseases; lacrimalapparatus diseases; lacrimal duct obstruction; myopia; presbyopia; pupildisorders; refractive disorders and strabismus. Glaucoma can also beconsidered to be an anterior ocular condition because a clinical goal ofglaucoma treatment can be to reduce a hypertension of aqueous fluid inthe anterior chamber of the eye (i.e. reduce intraocular pressure).

A posterior ocular condition is a disease, aliment of condition whichprimarily effects or involves a posterior ocular region or site such aschoroid or sclera (in a position posterior to a plane through theposterior wall of the lens capsule), vitreous, vitreous chamber, retina,optic nerve (i.e. the optic disc), and blood vessels and nerves whichvascularize or innervate a posterior ocular region or site.

Thus, a posterior ocular condition can include a disease, ailment orcondition, such as for example, acute macular neuroretinopathy; Behcet'sdisease; choroidal neovascularization; diabetic uveitis; histoplasmosis;infections, such as fungal or viral-caused infections; maculardegeneration, such as acute macular degeneration, non-exudative agerelated macular degeneration and exudative age related maculardegeneration; edema, such as macular edema, cystoid macular edema anddiabetic macular edema; multifocal choroiditis; ocular trauma whichaffects a posterior ocular site or location; ocular tumors; retinaldisorders, such as central retinal vein occlusion, diabetic retinopathy(including proliferative diabetic retinopathy), proliferativevitreoretinopathy (PVR), retinal arterial occlusive disease, retinaldetachment, uveitic retinal disease; sympathetic opthalmia; VogtKoyanagi-Harada (VKH) syndrome; uveal diffusion; a posterior ocularcondition caused by or influenced by an ocular laser treatment;posterior ocular conditions caused by or influenced by a photodynamictherapy, photocoagulation, radiation retinopathy, epiretinal membranedisorders, branch retinal vein occlusion, anterior ischemic opticneuropathy, non-retinopathy diabetic retinal dysfunction, retinitispigmentosa, and glaucoma. Glaucoma can be considered a posterior ocularcondition because the therapeutic goal is to prevent the loss of orreduce the occurrence of loss of vision due to damage to or loss ofretinal cells or optic nerve cells (i.e. neuroprotection).

The term “biodegradable polymer” refers to a polymer or polymers whichdegrade in vivo, and wherein erosion of the polymer or polymers overtime occurs concurrent with or subsequent to release of the therapeuticagent. Specifically, hydrogels such as methylcellulose which act torelease drug through polymer swelling are specifically excluded from theterm “biodegradable polymer”. The terms “biodegradable” and“bioerodible” are equivalent and are used interchangeably herein. Abiodegradable polymer may be a homopolymer, a copolymer, or a polymercomprising more than two different polymeric units.

The term “treat”, “treating”, or “treatment” as used herein, refers toreduction or resolution or prevention of an ocular condition, ocularinjury or damage, or to promote healing of injured or damaged oculartissue. A treatment is usually effective to reduce at least one symptomof en ocular condition, ocular injury or damage.

The term “therapeutically affective amount” as used herein, refers tothe level or amount of agent needed to treat an ocular condition, orreduce or prevent ocular injury or damage without causing significantnegative or adverse side effects to the eye or a region of the eye. Inview of the above, a therapeutically effective amount of a therapeuticagent such as a prostamide or prostamide derivative, is an amount thatis effective in reducing at least one symptom of an ocular condition.

Intraocular implants have been developed which can release drug loadsover various time periods. These implants, which when inserted into aneye, such as the vitreous of an eye, provide therapeutic levels of aprostamide component for extended periods of time (e.g., for about 1week or more). The disclosed implants are effective in treating ocularconditions, such as ocular conditions associated with elevatedintraocular pressure, and more specifically in reducing at least onesymptom of glaucoma.

Methods for producing intraocular implants have also been developed. Forexample, the present invention encompasses therapeutic polymericmicroparticles and methods of making and using such microparticles. Asdisclosed herein, the microparticles may be oil-in-oil emulsifiedmicroparticles.

In one embodiment of the present invention, an intraocular implantcomprises a biodegradable polymer matrix. The biodegradable polymermatrix is one type of a drug release sustaining component. Thebiodegradable polymer matrix is effective in forming a biodegradableintraocular implant. The biodegradable intraocular implant comprises aprostamide component associated with the biodegradable polymer matrix.The matrix degrades at a rate effective to sustain release of an amountof the prostamide component for a time greater than about one week fromthe time in which the implant is placed in ocular region or ocular site,such as the vitreous of an eye.

The prostamide component of the implant includes one or more types ofprostamides, prostamide derivatives, salts thereof, and matures thereof.In certain implants, the prostamide component composes a compound havingthe formula (I)

wherein the dashed bonds represent a single or double bond which can bein the cis or trans configuration, A is an alkylene or alkenyleneradical having from two to six carbon atoms, which radical may beinterrupted by one or more oxide radicals and substituted with one ormore hydroxy, oxo, alkyloxy or akylcarboxy groups wherein said alkylradical comprises from one to six carbon atoms; B is a cycloalkylradical having from three to seven carbon atoms, or an aryl radical,selected from the group consisting of hydrocarbyl aryl and heteroarylradicals having from four to ten carbon atoms wherein the heteroatom isselected from the group consisting of nitrogen, oxygen and sulfur atoms;X is a radical selected from the group consisting of —OR⁴ and —N(R⁴)₂wherein R⁴ is selected from the group consisting of hydrogen, a loweralkyl radical having from one to six carbon atoms,

wherein R⁵ is a lower alkyl radical having from one to six carbon atoms;Z is ═O or represents 2 hydrogen radicals; one of R₁ and R₂ is ═O, —OHor a —O(CO)R₆ group, and the other one is —OH or —O(CO)R₆ or R₁ is ═Oand R₂ is H, wherein R₆ is a saturated or unsaturated acyclichydrocarbon group having from 1 to about 20 carbon atoms, or —(CH₂ )mR₇wherein m is 0 or an integer of from 1 to 10, and R₇ is cycloalkylradical, having from three to seven carbon atoms, or a hydrocarbyl arylor heteroaryl radical, as defined above, or apharmaceutically-acceptable salt thereof, provided, however, that when Bis not substituted with a pendant heteroatom-containing radical, and Zis ═O, then X is not —OR⁴.

Pharmaceutically acceptable acid addition salts of the compounds of theinvention are those formed from acids which form non-toxic additionsalts containing pharmaceutically acceptable anions, such as thehydrochloride, hydrobromide, hydroiodide, sulfate, or bisulfate,phosphate or acid phosphate, acetate, maleate, fumarate, oxalate,lactate, tartrate, citrate, gluconate, saccharide and p-toluenesulphonate salts.

In more specific implants, the compound of the prostamide component hasthe following formula (II)

wherein y is 0 or 1, x is 0 or 1 and x+y are not both 1, Y is a radicalselected from the group consisting of alkyl, halo, nitro, amino, thiol,hydroxy, alkyloxy, alkylcarboxy and halo substituted alkyl, wherein saidalkyl radical composes from one to six carbon atoms, n is 0 or aninteger of from 1 to 3 and R₃ is ═O, —OH or —O(CO)R₆.

In additional implants, the compound of the prostamide component has thefollowing formula (III)

wherein hatched lines indicate the α configuration and solid trianglesindicate the β configuration.

In certain implants, the compound of the prostamide component has thefollowing formula (IV)

wherein Y¹ is Cl or trifluoromethyl, such as the compound having thefollowing formula (V)

and the 9- and/or 11- and/or 15 esters thereof.

In at least one type of intraocular implant, the prostamide componentcomprises a compound having the following formula (VI)

The compound having the formula VI is also known as bimatoprost and ispublicly available in a topical ophthalmic solution under the tradename,Lumigan® (Allergan, Inc., Calif.).

Thus, the implant may comprise a therapeutic component which comprises,consists essentially of, or consists of bimatoprost, a salt thereof, ormixtures thereof.

The prostamide component may be in a particulate or powder form and itmay be entrapped by the biodegradable polymer matrix. Usually,prostamide particles will have art effective average size less thanabout 3000 nanometers. In certain implants, the particles may have aneffective average particle size about an order of magnitude smaller than3000 nanometers. For example, the particles may have an effectiveaverage particle size of less than about 500 nanometers. In additionalimplants, the particles may have an effective average particle size ofless than about 400 nanometers, and in still further embodiments, a sizeless than about 200 nanometers.

The prostamide component of the implant is preferably from about 10% to90% by weight of the implant. More preferably, the prostamide componentis from about 20% to about 80% by weight of the implant. In a preferredembodiment, the prostamide component comprises about 20% by weight ofthe implant (e.g., 15%-25%). In another embodiment, the prostamidecomponent comprises about 50% by weight of the implant.

Suitable polymeric materials or compositions for use in the implantinclude those materials which are compatible, that is biocompatible,with the eye so as to cause no substantial interference with thefunctioning or physiology of the eye. Such materials preferably are atleast partially and more preferably substantially completelybiodegradable or bioerodible.

Examples of useful polymeric materials include, without limitation, suchmaterials derived from and/or including organic eaters and organicethers, which when degraded result in physiologically acceptabledegradation products, including the monomers. Also, polymeric materialsderived from and/or including, anhydrides, amides, orthoesters and thelike, by themselves or in combination with other monomers, may also finduse. The polymeric materials may be addition or condensation polymers,advantageously condensation polymers. The polymeric materials may becross-linked or non-cross-linked, for example not more than lightlycross-linked, such as less than about 5%, or less than about 1% of thepolymeric material being cross-linked. For the most part, besides carbonand hydrogen, the polymers will include at least one of oxygen andnitrogen, advantageously oxygen. The oxygen may be present as oxy, e.g.hydroxy or ether, carbonyl, e.g. non-oxo-carbonyl, such as carboxylicacid ester, and the like. The nitrogen may be present as amide, cyanoand amino. The polymers set forth in Heller, Biodegradable Polymers inControlled Drug Delivery, In: CRC Critical Reviews in Therapeutic DrugCarrier Systems, Vol. 1, CRC Press, Boca Raton, Fla. 1987, pp 39-90,which describes encapsulation for controlled drug delivery, may find usein the present implants.

Of additional interest are polymers of hydroxyaliphatic carboxylicacids, either homopolymers or copolymers, and polysaccharides.Polyesters of interest include polymers of D-lactic acid, L-lactic acid,racemic lactic acid, glycolic acid, polycaprolactone, and combinationsthereof. Generally, by employing the L-lactate or D-lactate, a slowlyeroding polymer or polymeric material is achieved, while erosion issubstantially enhanced with the lactate racemate.

Among the useful polysaccharides are, without limitation, calciumalginate, and functionalized celluloses, particularlycarboxymethylcellulose esters characterized by being water insoluble, amolecular weight of about 5 kD to 500 kD, for example.

Other polymers of interest include, without limitation, polyvinylalcohol, polyesters, polyethers and combinations thereof which arebiocompatible and may be biodegradable and/or bioerodible.

Some preferred characteristics of the polymers or polymeric materialsfor use in the present invention may include biocompatibility,compatibility with the therapeutic component, ease of use of the polymerin making the drug delivery systems of the present invention, ahalf-life in the physiological environment of at least about 6 hours,preferably greater than about one day, not significantly increasing theviscosity of the vitreous, and wafer insolubility.

The biodegradable polymeric materials which are included to form thematrix are desirably subject to enzymatic or hydrolytic instability.Water soluble polymers may be cross-linked With hydrolytic orbiodegradable unstable cross-links to provide useful water insolublepolymers. The degree of stability can be varied widely, depending uponthe choice of monomer, whether a homopolymer or copolymer is employed,employing mixtures of polymers, and whether the polymer includesterminal acid groups.

Equally important to controlling the biodegradation of the polymer andhence the extended release profile of the implant is the relativeaverage molecular weight of the polymeric composition employed in theimplant. Different molecular weights of the same or different polymericcompositions may be included in the implant to modulate the releaseprofile. In certain implants, the relative average molecular weight ofthe polymer will range from about 9 to about 64 kD, usually from about10 to about 54 kD, and more usually from about 12 to about 45 kD.

In some implants, copolymers of glycolic acid and lactic acid are used,where the rate of biodegradation is controlled by the ratio of glycolicadd to lactic acid. The most rapidly degraded copolymer has roughlyequal amounts of glycolic add and lactic acid. Homopolymers, orcopolymers having ratios other than equal, are more resistant todegradation. The ratio of glycolic acid to lactic acid will also affectthe brittleness of the implant, where a more flexible implant isdesirable for larger geometries. The % of polylactic acid in thepolylactic acid polyglycolic acid (PLGA) copolymer can be 0-100%,preferably about 15-85%, more preferably about 35-65%. In some implants,a 50/50 PLGA copolymer is used.

The biodegradable polymer matrix of the intraocular implant may comprisea mixture of two or more biodegradable polymers. For example, theimplant may comprise a mixture of a first biodegradable polymer and adifferent second biodegradable polymer. One or more of the biodegradablepolymers may have terminal acid groups.

Release of a drug from an erodible polymer is the consequence of severalmechanisms or combinations of mechanisms. Some of these mechanismsinclude desorption from the implant's surface, dissolution, diffusionthrough porous channels of the hydrated polymer and erosion. Erosion canbe bulk or surface or a combination of both. As discussed herein, thematrix of the intraocular implant may release drug at a rate effectiveto sustain release of an amount of the prostamide component for morethan one week after implantation into an eye. In certain implants,therapeutic amounts of the prostamide component are released for no morethan about 30-35 days after implantation. For example, an implant maycomprise bimatoprost, and the matrix of the implant degrades at a rateeffective to sustain release of a therapeutically effective amount ofbimatoprost for about one month after being placed in an eye. As anotherexample, the implant may comprise bimatoprost, and the matrix releasesdrug at a rate effective to sustain release of a therapeuticallyeffective amount of bimatoprost for more than forty days, such as forabout six months.

One example of the biodegradable intraocular implant comprises anprostamide component associated with a biodegradable polymer matrix,which comprises a mixture of different biodegradable polymers. At leastone of the biodegradable polymers is a polylactide having a molecularweight of about 63.3 kD. A second biodegradable polymer is a polylactidehaving a molecular weight of about 14 kD. Such a mixture is effective insustaining release of a therapeutically effective amount of theprostamide component for a time period greater than about one month fromthe time the implant is placed in an eye.

Another example of a biodegradable intraocular implant comprises anprostamide component associated with a biodegradable polymer matrix,which comprises a mixture of different biodegradable polymers, eachbiodegradable polymer having an inherent viscosity from about 0.16 dl/gto about 1.0 dl/g. For example, one of the biodegradable polymers mayhave an inherent viscosity of about 0.3 dl/g. A second biodegradablepolymer may have an inherent viscosity of about 1.0 dl/g. Additionalimplants may comprise biodegradable polymers that have an inherentviscosity between about 0.2 dl/g and 0.5 dl/g. The inherent viscositiesidentified above may be determined in 0.1% chloroform at 25° C.

One particular implant comprises bimatoprost associated with acombination of two different polylactide polymers. The bimatoprost ispresent in about 20% by weight of the implant. One polylactide polymerhas a molecular weight of about 14 kD and an inherent viscosity of about0.3 dl/g, and the other polylactide polymer has a molecular weight ofabout 63.3 kD and an inherent viscosity of about 1.0 dl/g. The twopolylactide polymers are present in the implant in a 1:1 ratio. Such animplant may be effective in releasing the bimatoprost for more than twomonths. The implant is provided in the form of a rod or a filamentproduced by an extrusion process.

The release of the prostamide component from the intraocular implantcomprising a biodegradable polymer matrix may include an initial burstof release followed by a gradual increase in the amount of theprostamide component released, or the release may include an initialdelay in release of the prostamide component followed by an increase inrelease. When the implant is substantially completely degraded, thepercent of the prostamids component that has been released is about onehundred. Compared to easting implants, the implants disclosed herein donot completely release, or release about 100% of the prostamidecomponent, until after about one week of being pieced in an eye.

It may be desirable to provide a relatively constant rate of release ofthe prostamide component from the implant over the life of the implant.For example, it may be desirable for the prostamide component to bereleased in amounts from about 0.01 μg to about 2 μg per day for thelife of the implant. However, the release rate may change to eitherincrease or decrease depending on the formulation of the biodegradablepolymer matrix. In addition, the release profile of the prostamidecomponent may include one or more linear portions and/or one or morenon-linear potions. Preferably, the release rate is greater than zeroonce the implant has begun to degrade or erode.

The implants may be monolithic, i.e. having the active agent or agentshomogenously distributed through the polymeric matrix, or encapsulated,where a reservoir of active agent is encapsulated by the polymericmatrix. Due to ease of manufacture, monolithic implants are usuallypreferred aver encapsulated forms. However, the greater control affordedby the encapsulated, reservoir-type implant may be of benefit in somecircumstances, where the therapeutic level of the drug falls within anarrow window. In addition, the therapeutic component, including theprostamide component may be distributed in a non-homogenous pattern inthe matrix. For example, the implant may include a portion that has agreater concentration of the prostamide component relative to a secondportion of the implant.

The intraocular implants disclosed herein may have a size of betweenabout 5 μm and about 10 mm, or between about 10 μm and about 1 mm foradministration with a needle, greater than 1 mm, or greater than 2 mm,such as 3 mm or up to 10 mm, for administration by surgicalimplantation. For needle-injected implants, the implants may have anyappropriate length se long as the diameter of the implant permits theimplant to move through a needle. For example, implants having a lengthof about 6 mm to about 7 mm have been injected into an eye. The implantsadministered by way of a needle should have a diameter that is less thanthe inner diameter of the needle. In certain implants, the diameter isless than about 500 μm. The vitreous chamber in humans is able toaccommodate relatively large implants of varying geometries, havinglengths of, for example, 1 to 10 mm. The implant may be a cylindricalpellet (e.g., rod) with dimensions of about 2 mm×0.75 mm diameter. Orthe implant may be a cylindrical pellet with a length of about 7 mm toabout 10 mm, and a diameter of about 0.75 mm to about 1.5 mm.

The implants may also be at least somewhat flexible so as to facilitateboth insertion of the implant in the eye, such as in the vitreous, andaccommodation of the implant. The total weight of the implant is usuallyabout 250-5000 μg, more preferably about 500-1000 μg. For example, animplant may be about 500 μg, or about 1000 μg. For non-humanindividuals, the dimensions and total weight of the implant(s) may belarger or smaller, depending on the type of individual. For example,humans have a vitreous volume of approximately 3.8 ml, compared withapproximately 30 ml for horses, and approximately 60-100 ml forelephants. An implant sized for use in a human may be scaled up or downaccordingly for other animals, for example, about 8 times larger for animplant for a horse, or about, for example, 26 times larger for animplant for an elephant.

Thus, implants can be prepared where the center may be of one materialand the surface may have one or more layers of the same or a differentcomposition, where the layers may be cross-linked, or of a differentmolecular weight, different density or porosity, or the like. Forexample, where it is desirable to quickly release an initial bolus ofdrug, the center may be a polylactate coated with apolylactate-polyglycolate copolymer, so as to enhance the rate ofinitial degradation. Alternatively, the center may be polyvinyl alcoholcoated with polytactate, so that upon degradation of the polylactateexterior the center would dissolve and be rapidly washed out of the eye.

The implants may be of any geometry including fibers, sheets, films,microspheres, spheres, circular discs, plaques and the like. The upperlimit for the implant size will be determined by factors such astoleration for the implant, size limitations on insertion, ease ofhandling, etc. Where sheets or films are employed, the sheets or filmswill be in the range of at least about 0.5 mm×0.5 mm, usually about 3-10mm×5-10 mm with a thickness of about 0.1-1.0 mm for ease of handling.Where fibers me employed, the fiber diameter will generally be in therange of about 0.05 to 3 mm and the fiber length will generally be inthe range of about 0.5-10 mm. Spheres may be in the range of about 0.5μm to 4 mm in diameter, with comparable volumes for other shapedparticles.

The size and form of the implant can also be used to control the rate ofrelease, period of treatment, and drug concentration at the site ofimplantation. Larger implants with deliver a proportionately largerdose, but depending on the surface to mass ratio, may have a slowerrelease rate. The particular size and geometry of the implant are chosento suit the site of implantation.

The proportions of the prostamide component, polymer, and any othermodifiers may be empirically determined by formulating several implantswith varying proportions. A USP approved method for dissolution orrelease test can be used to measure the rate of release (USP 23; NF 18(1995) pp, 1790-1798). For example, using the infinite sink method, aweighed sample of the implant is added to a measured volume of asolution containing 0.9% NaCl in water, where the solution volume willbe such that the drug concentration is after release is less than 5% ofsaturation. The mixture is maintained at 37° C. and stirred slowly tomaintain the implants in suspension. The appearance of the dissolveddrug as a function of time may be followed by various methods known inthe art, such as spectrophotometrically, HPLC, mass spectroscopy, etc.until the absorbance becomes constant or until greater than 90% of thedrug has been released.

In addition to the prostamide or prostamide derivatives included in theintraocular implants disclosed herein, the intraocular implants may alsoinduce one or more additional ophthalmically acceptable therapeuticagents. For example, the implant may include one or more antihistamines,one or more antibiotics, one or more beta blockers, one or moresteroids, one or more antineoplastic agents, one or moreimmunosuppressive agents, one or more antiviral agents, one or moreantioxidant agents, and mixtures thereof.

Pharmacologic or therapeutic agents which may find use in the presentsystems, include, without limitation, those disclosed in U.S. Pat. No.4,474,451, columns 4-6 and U.S. Pat. No. 4,327,725, columns 7-8.

Examples of antihistamines include, and are not limited to, loradatine,hydroxyzine, diphenhydramine, chlorpheniramine, brompheniramine,cyproheptadine, terfenadine, clemastine, triprolidine, carbinoxamine,diphenylpyraline, phenindamine, azatadine, tripelennamine,dexchlorphentramine, dexbrompheniramine, methdilazine, and trimprazinedoxylamine, pheniramine, pyrilamine, chlorcyclizine, thonzylamine, andderivatives thereof.

Examples of antibiotics include without limitation, cefazolin,cephradine, cefactor, cephapirin, ceftizoxime, cefoperazone, cefotetan,cefutoxmine, cefotaxime, cefadroxil, ceftazidime, cephalexin,cephalothin, cefamandole, cefoxitin, cefonicid, cefonsnide, ceftriaxone,cefaoroxil, caphradine, cefuroxime, ampicillin, amoxicillin,cyclacillin, ampicillin, penicillin G, penicillin V potassium,piperacillin, oxacillin, bacampicillin, cloxacillin, ticarcillin,azlocillin, carbenicillin, methicillin, nafcillin, erythromycin,tetracycline, doxycycline, minocycline, aztreonam, chloramphenicol,ciprofloxacin hydrochloride, clindamycin, metronidazole, gentamicin,lincomycin, tobramycin, vancomycin, polymyxin B sulfate, colistimethate,colistin, azithromycin, augmentin, sulfamethoxazole, trimethoprim, andderivatives thereof.

Examples of beta blockers include acebutolol, atenolol, labetatol,metoprolol, propranolol, timolol, and derivatives thereof.

Examples of steroids include corticosteroids, such as cortisone,prednisolone, flurometholone, dexamethasone, madrysone, loteprednol,fluazacort, hydrocortisone, prednisone, betamethasone, prednisone,methylprednisolone, riamcinolone hexacatonide, paramethasone acetate,diflorasone, fluocinonide, fluocinolone, triamcinolone, derivativesthereof, and mixtures thereof.

Examples of antineoplastic agents include adriamycin, cyclophosphamide,actinomycin, bleomycin, duanorubicin, doxorubicin, epirubicin,mitomycin, methotrexate, fluorouracil, carboplatin, carmustine (BCNU),methyl-CCNU, cisplatin, etoposide, interferons, camptothecin andderivatives thereof, phenesterine, taxol and derivatives thereof,taxotere and derivatives thereof, vinblastine, vincristine, tamoxifen,etoposide, piposulfan, cyclophosphamide, and flutamids, and derivativesthereof.

Examples of immunosuppresive agents include cyclosporine, azathioprine,tacrolimus, and derivatives thereof.

Examples of antiviral agents include interferon gamma, zidovudine,amantadine hydrochloride, ribavirin, acyclovir, valciclovir,dideoxycytidine, phosphonoformic acid, ganciclovir, and derivativesthereof.

Examples of antioxidant agents include ascorhate, alpha-tocopharol,mannitol, reduced glutathione, various carotenoids, cysteine, uric acid,taurine, tyrosine, superoxide dismutase, lutein, zeaxanthin,cryotpxanthin, astazanthin, lycopene, N-acetyl-cysteine, camosine,gamma-glutamylcysteine, quercitin, lactoferrin, dihydrolipoic acid,citrate, Ginkgo Biloba extract, tea catechins, bilberry extract,vitamins E or esters of vitamin E, retinyl palmitate, and derivativesthereof.

Other therapeutic agents include squalamine, carbonic anhydraseinhibitors, alpha-2 adrenergic receptor agonists, antiparasitics,antifungals, and derivatives thereof.

The amount of active agent or agents employed in the implantindividually or in combination, will vary widely depending on theeffective dosage required and the desired rate of release from theimplant. Usually the agent will be at least about 1, more usually atleast about 10 weight percent of the implant, and usually not more thanabout 80, more usually not more than about 40 weight percent of theimplant.

Some of the present implants may comprise a prostamide component thatcomprises a combination of two or more different prostamide derivatives.One implant may comprise a combination of bimatoprost and latanoprost.Another implant may comprise a combination of bimatoprost andtravoprost.

As discussed herein, the present implants may comprise additionaltherapeutic agents. For example, one implant may comprise a combinationof bimatoprost and a beta-adrenergic receptor antagonist. Morespecifically, the implant may comprise a combination of bimatoprost andTimolol®. Or, an implant may comprise a combination of bimatoprost and acarbonic anyhdrase inhibitor. For example, the implant may comprise acombination of bimatoprost and dorzolamide (Trusopt®).

In addition to the therapeutic component, the intraocular implantsdisclosed herein may include or may be provided in compositions thatinclude effective amounts of buffering agents, preservatives and thelike. Suitable water soluble buffering agents include, withoutlimitation, alkali and alkaline earth carbonates, phosphates,bicarbonates, citrates, borates, acetates, succinates and the like, suchas sodium phosphate, citrate, borate, acetate, bicarbonate, carbonateand the like. These agents advantageously present in amounts sufficientto maintain a pH of the system of between about 2 to about 9 and morepreferably about 4 to about 8. As such the buffering agent may be asmuch as about 5% by weight of the total implant. Suitable water solublepreservatives include sodium bisulfite, sodium bisulfate, sodiumthiosulfate, ascorbate, benzalkonium chloride, chlorobutanol,thimerosal, phenylmercuric acetate, phenylmercuric borate,phenylmercuric nitrate, parabens, methylparaben, polyvinyl alcohol,benzyl alcohol, phenylethanol and the like and mixtures thereof. Theseagents may be present in amounts of from 0.001 to about 5% by weight andpreferably 0.01 to about 2% by weight. In at least one of the presentimplants, a benzylalkonium chloride preservative is provided in theimplant, such as when the prostamide component consists essentially ofbimatoprost.

In some situations mixtures of implants may be utilized employing thesame or different pharmacological agents. In this way, a cocktail ofrelease profiles, giving a biphasic or triphasic release with a singleadministration is achieved, where the pattern of release may be greatlyvaried.

Additionally, release modulators such as those described in U.S. Pat.No. 5,869,079 may be included in the implants. The amount of releasemodulator employed will be dependent on the desired release profile, theactivity of the modulator, and on the release profile of the prostamidecomponent in the absence of modulator. Electrolytes such as sodiumchloride and potassium chloride may also be included in the implant.Where the buffering agent or enhancer is hydrophilic, it may also act asa release accelerator. Hydrophilic additives act to increase the releaserates through faster dissolution of the material surrounding the drugparticles, which increases the surface area of the drug exposed, therebyincreasing the rate of drug bioerosion. Similarly, a hydrophobicbuffering agent or enhancer dissolve more slowly, slowing the exposureof drug particles, and thereby slowing the rate of drug bioerosion.

In certain implants, an implant comprising bimatoprost and abiodegradable polymer matrix able to release or deliver an amount ofbimatoprost between about 0.1 mg to about 0.05 mg for about 3-6 monthsafter implantation into the eye. The implant may be configured as a rodor a wafer. A rod-shaped implant may be derived from filaments extrudedfrom a 720 μm nozzle and cut into 1 mg size. A wafer-shaped implant maybe a circular disc having a diameter of about 2.5 mm, a thickness ofabout 0.127 mm, and a weight of about 1 mg.

Various techniques may be employed to produce the implants describedherein. Useful techniques include, but are not necessarily limited to,solvent evaporation methods, phase separation methods, interfacialmethods, molding methods, injection molding methods, extrusion methods,co-extrusion methods, carver press method, die cutting methods, neatcompression, combinations thereof and the like.

Specific methods are discussed in U.S. Pat. No 4,997,652. Extrusionmethods may be used to avoid the need for solvents in manufacturing.When using extrusion methods, the polymer and drug are chosen so as tobe stable at the temperatures required for manufacturing, usually atleast about 85 degrees Celsius. Extrusion methods use temperatures ofabout 25 degrees C. to about 150 degrees C., more preferably about 65degrees C. to about 130 degrees C. An implant may be produced bybringing the temperature to about 60 degrees C. to about 150 degrees C.for drug/polymer mixing, such as about 130 degrees C., for a time periodof about 0 to 1 hour, 0 to 30 minutes, or 5-15 minutes. For example, atime period may be about 10 minutes, preferably about 0 to 5 min. Theimplants are then extruded at a temperature of about 60 degrees C. toabout 130 degrees C., such as about 78 degrees C.

In addition, the implant may be coextruded so that a coating is formedover a core region during the manufacture of the implant.

Compression methods may be used to make the implants, and typicallyyield implants with faster release rates than extrusion methods.Compression methods may use pressures of about 50-150 psi, morepreferably about 70-80 psi, even more preferably about 76 psi, and usetemperatures of about 0 degrees C. to about 115 degrees C., morepreferably about 25 degrees C.

Another method comprises using an oil-in-oil emulsion process to producethe present implants, including the microparticle implants ormicroparticles.

In one embodiment, a method for producing therapeutic polymericmicroparticles comprises encapsulating a prostamide component with apolymeric component to form a population of prostamide-encapsulatedmicroparticles by an oil-in-oil emulsion process. Such microparticlesare effective in treating one or more ocular conditions, as describedherein, and are suitable for administration to a parent into thevitreous or outside of the vitreous of a patient's eye. The therapeuticactivity of the prostamide component remains stable during storage ofthe implants which may be attributed to the particular encapsulated formof the implants.

In more detail, a method of forming microparticles comprises forming anoil-in-oil emulsion containing the prostamide component and thepolymeric component. For example, the method may include mixing orcombining a plurality, such as two or more, non-aqueous liquidcompositions to form an emulsion. In one embodiment, a first compositionmay comprise an organic solvent, and a second composition may comprisean oil. At least one of the compositions contains the prostamidecomponent, the polymeric component, or the prostamide component and thepolymeric component.

The method also comprises drying the emulsion to form a dried emulsionproduct. The drying can be achieved using one or more techniques toremove the liquid from the emulsified product. For example, the dryingprocess can include increasing the temperature of or near the emulsifiedproduct to facilitate evaporation of the liquid, can include the use ofa vacuum to facilitate removal of the liquid, can include centrifugationto separate solid from the liquid, and combinations thereof.

The dried emulsion product can then be contacted with a solvent to forma solvent containing composition. Adding a solvent to the dried emulsionproduct, or otherwise contacting the product with the solvent results inthe product being suspended in a volume of the liquid solvent. Thecontacting can include a step of stirring or mining the combination ofthe solvent and dried emulsion product to form a suspension of the driedemulsion product in the solvent. The suspension can include particles ofthe dried emulsion product. For example, particles of various sizes andshapes, including microparticles and or microspheres.

After forming the solvent containing composition, the method cancomprise removing the solvent from the solvent-containing composition toform a population of mioroparticles that comprise the prostamidecomponent and the polymeric component. The removing can include one ormore steps of centrifuging and/or rinsing intermediate compositions, andcan include one or more steps of drying the resulting composition. Theresulting products are encapsulated micromparticles or microimplantsthat comprise a prostamide component encapsulated by a polymericcomponent, such as a biodegradable polymer coating.

As discussed herein, the prostamide component can comprises a singletype of prostamide derivative or derivatives. In certain embodiments,the prostamide component comprises at least one prostamide derivativeselected from the group consisting of bimatoprost, salts thereof, andmixtures thereof. In a further embodiment, the prostamide componentconsists essentially of bimatoprost.

In additional embodiments, the prostamide component can comprisecombinations of two or more different prostamide derivatives, such as acombination of bimatoprost and latanoprost, bimatoprost and travoprost,and the like.

The present methods are effective in producing encapsulated prostamidecomponent microparticles that maintain or preserve a substantialportion, if not all, of the therapeutic activity after a terminalsterilization procedure. If can be understood, that the present methodsmay also comprise a step of terminally sterilizing the microparticles.The microparticles can be sterilized before packaging or in theirpackaging. Sterilization of packages containing the presentmicroparticles or implants is often preferred. The method may compriseexposing the present microparticles or implants to sterilizing amountsof gamma radiation, e-beam radiation, and other terminal sterilizationproducts. In one embodiment, a method may comprise a step of exposingthe present microparticles to gamma radiation at a dose of about 25 kGy.

As discussed herein, the polymeric component recited in the presentmethod may comprise a biodegradable polymer or biodegradable copolymer.In at least one embodiment, the polymeric component comprises a poly(lactide-co-glycolide) PLGA copolymer. In a further embodiment, the PLGAcopolymer has a lactide/glycolide ratio of 75/25. In a still furtherembodiment, the PLGA copolymer has at least one of a molecular weight ofabout 63 kilodeltons and an inherent viscosity of about 0.6 dL/g.

The present methods may also compose a step of forming a firstcomposition which comprises a prostamide component, a polymericcomponent, and an organic solvent, and a step of forming a secondoil-containing composition, and mixing the first composition and thesecond oil-containing composition.

The present methods may also comprise evaporating the oil-in-oilemulsion to form an evaporated product, as described hereto.

Further, the methods may comprise a step of suspending the evaporatedproduct in a solvent before removing the solvent from the solventcontaining composition. Such a step can be understood to be a way offorming a suspension.

As one example, a method of forming encapsulated bimatoprostbiodegradable microparticles comprises forming an oil-in-oil emulsioncomprising the bimatoprost and PLGA, evaporating the liquid from theemulsion to form an evaporated product, suspending and rinsing theevaporated product, and drying the evaporated product.

In accordance with the disclosure herein, an embodiment of the presentinvention is a population of microparticles that comprise a polymericcomponent encapsulating a prostamide component in the form of oil-in-oilemulsified microparticles. In one specific embodiment, the polymericcomponent comprises a PLGA copolymer and the prostamide componentcomprises at least one prostamide derivative selected from the groupconsisting of bimatoprost, salts thereof, and mixtures thereof.

The resulting population may be a terminally sterilized population ofmicroparticles. Terminally sterilized microparticles retain theirtherapeutic activity during storage and therefore can provide successfultreatment to patients. In certain embodiments, a major portion of theprostamide component of the terminally sterilized microparticles remainsstable. For example, in certain embodiments, at least 80% of theprostamide component remains stable after sterilization. In furtherembodiments, at least 90%, at least 95%, or at least 99% of theprostamide component remains stable.

In addition, the present population of microparticles may have a maximumparticle diameter less than about 200 μm. In certain embodiments, thepopulation of microparticles has an average or mean particle diameterless than about 50 μm. In further embodiments, the population ofmicroparticles has a mean particle diameter from about 30 μm to about 50μm.

The present microparticles are structured or configured to release theprostamide component for extended periods of time at controlled rates.In some embodiments, the prostamide component is released at asubstantially linear rate (e.g., a single rate) over the life of themicroparticles (e.g., until the microparticles fully degrade). Otherembodiments are capable of releasing the prostamide component atmultiple tales or different rates over the life of the microparticles.The rate at which the microparticles degrade can vary, as discussedherein, and therefore, the present microparticles can release theprostamide component for different periods of time depending on theparticular configuration and materials of the microparticles. In atleast one embodiment, a microparticle can release about 1% of theprostamide component in the microparticles per day. In a furtherembodiment, the microparticles may have a release rate of about 0.7% perday when measured in vitro. Thus, over a period of about 40 days, about30% of the prostamide component may have been released.

As discussed herein, the amount of the prostamide component present inthe microparticles can vary. In certain embodiments, the about 10% wt/wtof the microparticles is the prostamide component. In furtherembodiments, the prostamide component constitutes about 5% wt/wt of themicroparticles.

The implants, including the population of microparticles, of the presentinvention may be inserted into the eye, for example the vitreous chamberof the eye, by a variety of methods, including placement by forceps orby trocar following making a 2-3 mm incision in the sclera. One exampleof a device that may be used to insert the implants into an eye isdisclosed in U.S. Patent Publication No. 2004/0054374. The method ofplacement may influence the therapeutic component or drug releasekinetics. For example, delivering the implant with a trocar may resultin placement of the implant deeper within the vitreous than placement byforceps, which may result in the implant being closer to the edge of toevitreous. The location of the implant may influence the concentrationgradients of therapeutic component or drug surrounding the element, andthus influence the release rates (e.g., an element placed closer to theedge of the vitreous may result a slower release rate). In addition, thepresent implants, including microparticles, can be administered to otherocular regions outside of the vitreous. Microparticles may beadministered to patients by administering an ophthalmically acceptablecomposition which comprises the microparticles to the patient. Forexample, microparticles may be provided in a liquid composition, asuspension, an emulsion, and the like, and administered topically or byinjection or implantation into one or more non-vitreal regions of theeye.

The present implants or microparticles are configured to release anamount of prostamide component effective to treat an ocular condition,such as by reducing at least one symptom of the ocular condition. Morespecifically, the implants or microparticles may be used in a method totreat glaucoma, such as open angle glaucoma, ocular hypertension,chronic angle-closure glaucoma, with patent iridotomy, psuedoexfoliativeglaucoma, and pigmentary glaucoma. By implanting the prostamidecomponent-containing implants into the vitreous of an eye, it isbelieved that the prostamide component is effective to enhance aqueoushumour flow thereby reducing intraocular pressure. In addition,placement of the microparticles described herein outside of the vitreouscan also provide similar therapy.

The implants disclosed herein may also be configured to release theprostamide component or additional therapeutic agents, as describedabove, which to prevent or treat diseases or conditions, such as thefollowing:

MACULOPATHIES/RETINAL DEGENERATION; Non-Exudative Age Related MacularDegeneration (ARMD), Exudative Age Related Macular Degeneration (ARMD),Choroidal Neovascularization, Diabetic Retinopathy, Acute MacularNeuroretinopathy, Central Serous Chorioretinopathy, Cystoid MacularEdema, Diabetic Macular Edema.

UVEITIS/RETINITIS/CHOROIDITIS: Acute Multifocal Placoid PigmentEpithellopathy, Behcet's Disease, Birdshot Retinocharoidopathy,Infectious (Syphilis, Lyme, Tuberculosis, Toxoplasmosis), IntermediateUveitis (Pars Planitis), Multifocal Choroiditis, Multiple EvanescentWhile Dot Syndrome (MEWDS), Ocular Sarcoidosis, Posterior Scleritis,Serpignous Choroiditis, Subretinal Fibrosis and Uveitis Syndrome,Vogt-Koyanagi-Harada Syndrome.

VASCULAR DISEASES/EXUDATIVE DISEASES: Coat's Disease, ParafovealTelangiectasis, Papillophlebitis, Frosted Branch Angitis, Sickle CellRetinopathy and other Hemoglobinopathies, Angloid Streaks, FamilialExudative Vitreoretinopathy.

TRAUMATIC/SURGICAL: Sympathetic Ophthalmia, Uveitis Retinal Disease,Retinal Detachment, Trauma, Laser, POT, Photocoagulation, HypoperfusionDuring Surgery, Radiation Retinopathy, Bone Marrow TransplantRetinopathy.

PROLIFERATIVE DISORDERS: Proliferative Vitreal Retinopathy andEpiretinal Membranes, Proliferative Diabetic Retinopathy.

INFECTIOUS DISORDERS: Ocular Histoplasmosis, Ocular Toxocariasis,Presumed Ocular Histoplasmosis Syndrome (POHS), Endophthalmitis,Toxoplasmosis, Retinal Diseases Associated with HIV Infection, ChoroidalDisease Associated with HIV Infection, Uveitic Disease Associated withHIV Infection, Viral Retinitis, Acute Retinal Necrosis, ProgressiveOuter Retinal Necrosis, Fungal Retinal Diseases, Ocular Syphilis, OcularTuberculosis, Diffuse Unilateral Subacute Neuroretinitis, Mylasis.

GENETIC DISORDERS: Systemic Disorders with Accosiated RetinalDystrophies, Congenital Stationary Night Blindness, Cone Dystrophies,Fundus Flavimaculatus, Best's Disease, Pattern Dystrophy of the RetinalPigmented Epithelium, X-Linked Retinoschisis, Sorsby's Fundus Dystrophy,Benign Concentric Maculopathy, Bietti's Crystalline Dystrophy,pseudoxanthoma elasticum.

RETINAL TEARS/HOLES: Retinal Detachment, Macular Hole, Giant RetinalTear.

TUMORS: Retinal Disease Associated with Tumors, Congenital Hypertrophyof the RPE, Posterior Uveal Melanoma, Choroidal Hemangioma, ChoroidalOsteoma, Choroidal Metastasis, Combined Hamartoma of the Retina andRetinal Pigmented Epithelium, Retinoblastoma, Vasoproliferative Tumorsof the Ocular Fundus, Retinal Astrocytoma, Intraocular Lymphoid Tumors.

MISCELLANEOUS: Punctate Inner Choroidopathy, Acute Posterior MultifocalPlacoid Pigment Epitheliopathy, Myopic Retinal Degeneration, AcuteRetinal Pigment Epithelitis and the like.

In one embodiment, an implant, such as the implants disclosed herein, isadministered to a posterior segment of an eye of a human or animalpatient, and preferably, a living human or animal. In at least oneembodiment, an implant is administered without accessing the subretinalspace of the eye. For example, a method of treating a patient mayinclude placing the implant directly into the posterior chamber of theeye. In other embodiments, a method of treating a patient may compriseadministering an implant to the patient by at least one of intravitrealinfection, subconjuctival injection, sub-tenon injections, retrobulbarinjection, and suprachoroidal injection.

In at least one embodiment, a method of reducing intraocular pressure inan eye of a patient comprises administering one or more implantscontaining a prostamide component, as disclosed herein to a patient byat least one of intravitreal injection, subconjuctival injection,sub-tenon injection, retrobulbar injection, and suprachoroidalinfection. A syringe apparatus including an appropriately sized needle,for example, a 22 gauge needle, a 27 gauge needle or a 30 gauge needle,can be effectively used to inject the composition with the posteriorsegment of an eye of a human or animal. Repeat injections are often notnecessary due to the extended release of the prostamide component fromthe implants.

In addition, for dual therapy approaches to treating an ocularcondition, the method may include one or more additional steps ofadministering additional therapeutic agents to the eye, such as bytopically administering compositions containing timolol, dorzolamide,and latoprost, among others.

In another aspect of the invention, kits and packages for treating anocular condition of the eye are provided, comprising: a) a containercomposing an extended release implant composing a therapeutic componentincluding a prostamide component, such as bimatoprost (Lumigan), and adrug release sustaining component; and b) instructions for use.Instructions may include steps of how to handle the implants, how toinsert the implants into an ocular region, and what to expect from usingthe implants.

In certain implants, the implant comprises a therapeutic component whichconsists essentially of bimatoprost, salts thereof, and mixturesthereof, and a biodegradable polymer matrix. The biodegradable polymermatrix may consist essentially of PLA, PLGA, or a combination thereof.When placed in the eye, the implant releases about 40% to about 60% ofthe bimatoprost to provide a loading dose of the bimatoprost withinabout one day after placement in the eye. Subsequently, the implantreleases about 1% to about 2% of the bimatoprost per day to provide asustained therapeutic effect. Such implants may be effective in reducingand maintaining a reduced intraocular pressure, such as below about 15mm Hg for several months, and potentially for one or two years.

Other implants disclosed herein may be configured such that the amountof the prostamide component that is released from the implant within twodays of being placed in the eye is less than about 95% of the totalamount of the prostamide component in the implant. In certain implants,95% of the prostamide component is not released until after about oneweek of being placed in an eye. In certain implants, about 50% of theprostamide component is released within about one day of placement inthe eye, and about 2% is released for about 1 month after being placedin the eye. In other implants, about 50% of the prostamide component isreleased within about one day of placement in the eye, and about 1% isreleased for about 2 months after being placed in the eye.

EXAMPLES Example 1 Manufacture and Testing of Implants ContainingBimatoprost and a Biodegradable Polymer Matrix

Biodegradable implants were made by combining bimatoprost with abiodegradable polymer composition. 800 mg of polylactic acid (PLA) wascombined with 200 mg of bimatoprost. The combination was dissolved in 25milliliters of dichloromethane. The mixture was placed in a vacuum at45° C. overnight to evaporate the dichloromethane. The resulting mixturewas in the form of a cast sheet. The cast sheet was cut and ground in ahigh shear grinder with dry ice until the particles could pass through asieve having a pore size of about 125 μm. The percent of bimatoprostpresent in the microparticles was analyzed using high pressure liquidchromatography (HPLC). The percent release of bimatoprost from themicroparticles was profiled using dialysis. The percent of bimatoprostremaining to the recovered particles was analyzed by HPLC.

The release profile is described in Table 1.

Elapsed Time Time Point (Days) Percent Released Percent Per Day Start 0— — 1 1.03 47.51 47.51 2 2.03 47.92 0.41 3 3.03 49.99 2.07 4 4.03 50.090.10 5 7.04 50.90 0.82

The percent loading of bimatoprost was 14.93%. The percent ofbimatoprost remaining in the recovered release particles was 4.94%.

Example 2 Extrusion Process and Compression of Manufacturing BimatoprostContaining Biodegradable Intraocular Implants

Bimatoprost is combined with a biodegradable polymer composition in amortar. The combination is mixed with a shaker set at about 96 RPM forabout 15 minutes. The powder blend is scraped off the wall of the mortarand is then remixed for an additional 15 minutes. The mixed powder blendis heated to a semi-molten state at specified temperature for a total of30 minutes, forming a polymer/drug melt.

Rods are manufactured by palletizing the polymer/drug melt using a 9gauge polytetraftuoroethylene (PTFE) tubing, loading the pellet into thebarrel and extruding the material at the specified core extrusiontemperature into filaments. The filaments are then cut into about 1 mgsize implants or drug delivery systems. The rods may have dimensions ofabout 2 mm long×0.72 mm diameter. The rod implants weigh between about900 μg and 1100 μg.

Wafers are formed by flattening the polymer melt with a Carver press ata specified temperature and cutting the flattened material into wafers,each weighing about 1 mg. The wafers have a diameter of about 2.5 mm anda thickness of about 0.13 mm. The wafer implants weigh between about 900μg and 1100 μg.

In-vitro release testing is performed by placing each implant into a 24mL screw cap vial with 10 mL of Phosphate Buffered Saline solution at37° C. 1 mL aliquots are removed and are replaced with equal volume offresh medium on day 1, 4, 7, 14, 28, and every two weeks thereafter.

Drug assays are performed by HPLC, which consists of a Wafers 2690Separation Module (or 2696), and a Waters 2996 Photodiode ArrayDetector. An Ultrasphere, C-18 (2), 5 μm; 4.6×150 mm column heated at30° C. is used for separation and the detector is set at about 264 nm.The mobile phase is (10:90) MeOH—buffered mobile phase with a flow rateof 1 mL/min and a total run time of 12 min per sample. The bufferedmobile phase may comprise (68:0.75:0.25:31) 13 mM 1-Heptane SulfonicAdd, sodium salt-glacial acetic acid-triethylamine-Methanol. The releaserates are determined by calculating the amount of drug being released ina given volume of medium over time in μg/day.

Polymers which may be used in the implants can be obtained fromBoehringer Ingelheim. Examples of polymer include: RG502, RG752, R202H,R203 and R206, and Purac PDLG (50/50), RG502 is (50:50)poly(D,L-lactide-co-glycolide), RG752 is (75:25)poly(D,L-lactide-co-glycolide), R202H is 100% poly(D,L-lactide) withacid end group or terminal acid groups, R203 and R206 are both 100%poly(D,L-lactide). Purac PDLG (50/50) is (50:50)poly(D,L-lactide-co-glycolide). The inherent viscosity of RG502, RG752,R202H, R203, R206, and Purac PDLG are 0.2, 0.2, 0.2, 0.3, 1.0, and 0.2dL/g, respectively. The average molecular weight of RG502, RG752, R202H,R203, R206, and Purac PDLG are, 11700, 11200, 6500, 14000, 63300, and9700 daltons, respectively.

Example 3 Bimatoprost/PLA/PLGA Intraocular Implants to Treat Glaucoma

A 72 year old female suffering from glaucoma in both eyes receives anintraocular implant containing bimatoprost and a combination of a PLAand PLGA in each eye. The implants weigh about 1 mg, and contain about500 mg of bimatoprost. One implant is placed in the vitreous of each eyeusing a syringe. In about two days, the patient reports a substantialrelief in ocular comfort. Examination reveals that the intraocularpressure has decreased, the average intraocular pressure measured at8:00 AM has decreased from 28 mm Hg to 14.3 mm Hg. The patient ismonitored monthly for about 6 months. Intraocular pressure levels remainbelow 15 mm Hg for six months, and the patient reports reduced oculardiscomfort.

Example 4 Bimatoprost/PLA Intraocular Implant to Reduce OcularHypertension

A 62 year old male presents with an intraocular pressure in his left eyeof 33 mm Hg. An implant containing 400 mg of bimatoprost and 600 mg ofPLA is inserted into the vitreous of the left eye using a trocar. Thepatient's intraocular pressure is monitored daily for one week, and thenmonthly thereafter. One day after implantation, the intraocular pressureis reduced to 18 mm Hg. By day 7 after implantation, the intraocularpressure is relatively stable at 14 mm Hg. The patient does notexperience any further signs of elevated intraocular pressure for 2years.

Example 5 Microencapsulation of a Prostamide Derivative

This example describes a process for producing microparticles thatinclude a prostamide derivative encapsulated by a biodegradable polymer.In the specific example, bimatoprost was used as the prostamidederivative. The procedures outlined herein can be used to makeencapsulated microparticles of other prostamide derivatives as well.

FIG. 10 is a flow chart illustrating the steps used in the method ofthis example.

As shown in FIG. 1, a first composition was formed by adding 100 mg ofbimatoprost to 20 mL of acetonitrile (CH₃CN) in an Erlenmeyer flask witha magnetic stirrer and stopper. The bimatoprost was solubilized in theacetonitirile. PLGA (900 mg) was added to the solubilized compositionand stirred until the PLGA was solubilized. This first composition canbe understood to be a discontinuous phase or an acetonitrile phasecomposition.

A second composition was formed by combining 800 mL of cottonseed oiland 12.8 mL of Span® 85 in a 1000 mL beaker. Span® 85 is a fatty acidcomposition which comprises oleic acid (C18:1) approx. 74%; linoleicacid (C18:2) approx. 7%; linolenic acid (C18:2) approx. 2%; palmitoleicacid (C16:1) approx. 7%; and palmitic acid (C16:0). Span is a registeredtrademark of ICI Americas, Inc., and the Span® 85 can be obtained frompublic sources, such as Sigma Aldrich. Other Span® products can also beused, such as Span® 80. This composition can be understood to be acontinuous phase or oil-containing composition.

An emulsion was formed by adding the first composition to the secondcomposition. The speed impeller was set at 350 rotations per minute(rpm) to stir the second composition. The first composition was added tothe stirring second composition, and the mixture was allowed to stir for90 minutes.

The emulsion was then evaporated under filter air flow for 45 hours at250 rpm air flow.

Hexane (250 mL) was added to the evaporated product and stirred for 1hour. Subsequently, the suspension was centrifuged at 7000 rpm for 10minutes.

The pellet containing microparticles was rinsed twice by centrifugingwith 100 mL of hexane. The microparticles were resuspended in 15 mL ofhexane.

The microspheres ware then dried under filter air flow overnight.

Microspheres were packaged under nitrogen and reduced temperatures tomaintain the temperature at about 5 C. The cooled microspheres weresterilized using gamma radiation (25-35 kGy).

FIGS. 2A, 2B, 2C, 2D, 2E, and 2F illustrate the chemical structure ofbimatoprost (AGN 192024, FIG. 2A), 15β bimatoprost (FIG. 2B); 5,6-transbimatoprost isomer (FIG. 2C); C1 acid of bimatoprost (FIG. 2D);triphenyphosphine oxide (TPPO; FIG. 2E); and 15-Keto bimatoprost (FIG.2F). Bimatoprost is the active ingredient and the other chemicals areimpurities that may be present. Bimatoprost has a molecular weight of415.6 g/mol, a solubility in water at room temperature of 3.2 mg/mL(which is slightly soluble), and a partition coefficient Log P of 2.4plus or minus 0.1. Bimatoprost is a non-ionisable compound.

The effects of gamma sterilization on the stability of bimatoprost arepresented in the following table (Table 2). The formula abbreviationscorrespond to compounds illustrated in FIGS. 2A-2F.

% wt/wt % wt/wt, 15- % wt/wt 5,6- Bimatoprost bimatoprost keto % wt/wt15β trans none sterilized 95.3 1.0 0.2 0.1 gamma 85.3 2.3 0.1 0.1sterilized

Gamma sterilization appeared to decrease the amount of activebimatoprost by about 10%. Gamma sterilization may also change the colorof the material (e.g., from white to a yellow/brown) and the consistencyof the material (e.g., from a fluffy powder to a more compact powder).

Two separate batches of microparticles were produced using PLGAcopolymers from different suppliers, as presented in Table 3, below

Lactide/Glycolide ratio Batch Random/Block Molecular Inherent SupplierNumber End-groups Weight Viscosity APT 1 75/25  63,200 Da 0.65 dL/gRandom Ester & Hydroxyl BPI 2 75/25 −97,100 Da 0.67 dL/g Random Ester &Hydroxyl

APT in Table 3 refers to Absorbable Polymer Technologies, and BPI refersto Birmingham Polymers, Inc. The PLGA obtained from APT appeared toprovide better results then PLGA from BPI.

High performance liquid chromatography was used to quantify bimatoprostand impurities present in the microparticles. Analytes were eluted froma Waters Symmetry® C18 reverse-phase column using a mobile phasecomposed of 72/18/10 (water/acetonitrile/methanol v/v/v) containing0.03% (w/v) trifluoroacetic acid. UV defection was performed at 210 nm.Chromatograms of a bimatoprost standard (FIG. 3A), a non-sterilized andsteritized placebo compositions (FIG. 3D and FIG. 3E), andnon-sterilized and sterilized bimatoprost microparticles (FIG. 3B andFIG. 3C) revealed that the microparticles did not contain detectableamounts of impurities as evidenced by the single absorption peek inFIGS. 3A-C.

Particle size was determined by suspending an aliquot of the bimatoprostmicrospheres in 1 mL of deionized water. To this, 100 μL of 10% Tween 80was added. The composition was sonicated for 5 minutes and vortexed for15 seconds. A Coulter LS230 apparatus or equivalent apparatus were usedto measure particle size. Mean particle diameters of tested batches werebetween about 30 μm and about 50 μm. Some particles had diameter up toabout 200 μm. These larger particles were observed in batches that werenot sieved. FIGS. 4A-4D illustrate particle diameters (differentialvolume and number) profile superposition for sterile and non sterileconditions. Each graph illustrates the particle diameter distributionfor a batch of sterile microspheres and non-sterile microspheres. Thedata reveal that sterilization did not significantly impact the particlesize distribution as evidenced by the substantial overlap in thedistribution curves. FIG. 4A illustrates volume % as a function ofparticle diameter for batch DL042 (top left panel), FIG. 4B illustratesnumber % as a function of particle diameter for batch DL042 (top rightpanel), FIG. 4C illustrates volume % as a function of particle diameterfor batch DL043 (bottom left panel), and FIG. 4D illustrates number % asa function of particle diameter for batch DL043 (bottom right panel).

Microscopic aspect was determined using the sample prepared for pediclesize determination, described above. Observations were performed atmagnification 5 and 20. FIGS. 5A-5F illustrate shapes of four differentnon-sterile and two different sterile batches of microspheres (FIG. 5Aand FIG. 5B (top two panels) and FIGS. 5C and 5E illustrate non-sterilebatches and FIG. 5D and FIG. 5F (bottom two right panels) illustratesterile batches of microspheres).

The dissolution profile for a batch of microparticles was monitored for28 and 42 days for sterile and non-sterile microspheres using dialysisbags and dissolution media. The dissolution media was phosphate buffer(pH 7.4) and ethanol in a ratio of 90/10. Samples were monitored at 37 Cin a shaker wafer bath at approximately 110 rpm. At each time point, analiquot of sample was collected and replaced by fresh media. Thedissolution profile for a batch of sterile and non-sterile microspheresis shown in FIG. 6. The dissolution rate for the non-sterilemicroparticles was about 0.7%/day (e.g., 30% released over 42 days). Thedissolution rata for the sterile batch initially appeared to be about0.7%/day and increased after about two weeks. FIG. 6 also shows thatbimatoprost was released faster from gamma sterilized microspheres thannon-sterilized microspheres.

Table 4 below provides information regarding the batches of microspheresprepared in accordance with the present methods and as discussed above.

Batch No. PLGA types/SPAN type Sterilized (Yes/No) DL040 PLGA APT 75/25/No iv 0.65/SPAN 80 DL041 APT/SPAN 85 No DL042 APT/SPAN 80 No DL042APT/SPAN 80 Yes DL043 APT/SPAN 80 No DL043 APT/SPAN 80 Yes

In Table 4, APT refers to the PLGA supplier, as discussed herein, ivrefers to inherent viscosity, and SPAN refers to the fatty acidcomposition described herein, and which is publicly available.

Table 5 below provides information regarding the amount of bimatoprostpresent in non-sterile microspheres. In these microspheres, bimatoprostwas present in an amount of about 5% w/w.

Batch No. Targeted loading % w/w bimatoprost DL040 10% 4.6 DL041 10% 5.1DL042 10% 4.8 DL043 Placebo ND

Batches DL042 and DL043 were gamma sterilized (25-35 kGy) in order toevaluate the stability of the active ingredient when encapsulated withinPLGA. The results are presented in Table 8 below.

% w/w Batch No. Targeted Loading bimatoprost % w/w keto DL042 10% 4.3 NDDL042 sterile 10% 4.2 ND DL043 Placebo ND ND DL043 sterile Placebo ND ND

All references, articles, publications and patents and patentapplications cited herein are incorporated by reference in theirentireties.

While this invention has bean described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

1. An intraocular implant comprising therapeutic polymeric microparticles, the microparticles made by the steps of: encapsulating a prostamide component with a polymeric component to form a population of prostamide-encapsulated microparticles by an oil-in-oil emulsion process, wherein the prostamide-encapsulated microparticles have an effective average particle size of less than about 3000 nanometers.
 2. The implant of claim 1, wherein the oil-in-oil emulsion process comprises forming an oil-in-oil emulsion containing the prostamide component and the polymeric component; drying the emulsion to form a dried emulsion product; contacting the dried emulsion product with a solvent to form a solvent-containing composition; and removing the solvent from the solvent-containing composition to form the population of microparticles comprising the prostamide component and the polymeric component. 3.-8. (canceled)
 9. The implant of claim 1, wherein the prostamide component of the microparticles so produced is encapsulated by the polymeric component to preserve therapeutic activity of the prostamide component after a terminal sterilization procedure.
 10. The implant of claim 1, wherein the polymeric component comprises a biodegradable polymer or biodegradable copolymer.
 11. The implant of claim 1, wherein the polymeric component comprises a poly(lactide-co-glycolide) PLGA copolymer.
 12. The implant of claim 11, wherein the PLGA copolymer has a lactide/glycolide ratio of 75/25 a molecular weight of about 63 kilodaltons, and an inherent viscosity of about 0.6 dL/g.
 13. The implant of claim 2, further comprising forming a first composition comprising the prostamide component, the polymeric component, and an organic solvent, and forming a second oil-containing composition, wherein the forming the oil-in-oil emulsion step comprises mixing the first composition and the second oil containing composition.
 14. The implant of claim 2, wherein the drying comprises evaporating the oil-in-oil emulsion to form an evaporated product.
 15. The implant of claim 14, further comprising suspending the evaporated product in the solvent before removing the solvent from the solvent-containing composition.
 16. The implant of claim 1, further comprising terminally sterilizing the polymeric microparticles. 17.-25. (canceled) 